1. Field of the Invention
The present invention relates to a vehicle air conditioner that is automatically controlled based on a temperature of the air detected by a non-contact temperature sensor.
2. Description of Related Art
US-2002-0053601A1 discloses an air conditioner for a vehicle. The air conditioner has an infrared temperature sensor, a controller, and a switch. The infrared temperature sensor is disposed in a center of an instrument panel of the vehicle. The sensor detects a temperature around a driver and occupants of a vehicle compartment. The controller controls the air conditioner based on the detected temperature. The switch is disposed on the instrument panel to be operated by the driver and the occupants.
U.S. Pat. No. 6,397,615 discloses another air conditioner for a vehicle. The air conditioner has a thermopile-type infrared temperature sensor, an air conditioning unit, and an electronic controller. The sensor detects the temperature around the driver and the occupants. The air conditioning unit controls the temperature and the air volume of conditioned air. The conditioned air is discharged from a blowout port that is disposed on a facing plate of a vehicle compartment (e.g., front surface of the instrument panel). The controller controls the air conditioning unit based on the temperature detected by the infrared temperature sensor.
In such air conditioners, as shown in FIG. 7, when the switch on the instrument panel is operated by the driver and the occupants, a detecting range 70b of the infrared sensor is interfered with hands of the driver and the occupants. This is because the infrared sensor (non-contact sensor) is disposed in the center of the instrument panel. In such an air conditioner, the infrared sensor fails to detect the temperature around the driver and the occupants accurately. As a result, the air conditioner cannot control conditioned air comfortably.
In addition, when the thermopile-type infrared temperature sensor is disposed under the blowout port, the sensor is affected by cooled air blowing from the blowout port. This is because the cooled air comes down from the blowout port while the air conditioner operates in a cooling mode.
In general, a thermopile-type infrared temperature sensor includes a can-like case, an infrared-absorbing film, and a thermocouple. The can-like case has a window. The infrared-absorbing film is disposed in the case. The film absorbs incident infrared rays through the window and transforms them into heat.
The heat causes temperature difference between a hot side junction and a cold side junction of the thermocouple. The temperature difference causes thermo-electromotive force between the junctions.
Namely, the incident infrared rays from the temperature-detecting range in the vehicle causes temperature difference between the hot and cold junctions of the thermopile. The temperature difference causes thermo-electromotive force or an electric potential difference from which the temperature of the temperature-detecting range is determined.
However, the sensor is affected by the cooled air, so that an uneven distribution of the temperature occurs in the can-like case. Due to the uneven distribution of the temperature in the can-like case, the temperature difference occurs. As a result, the air conditioning in the vehicle is disturbed.